If you’re anything at all like this writer, you don’t spend a lot of time inspecting brownies past the initial object identification phase, preferring to insert them directly into the mouth post-haste. But those with more of an aesthetic focus take great care to produce brownies with a glossy, attractive skin. [Adam Ragusea] decided to find out what it takes to get a perfect brownie skin, time after time.
After many, many trays of brownies, [Adam], with the assistance of [Dr. Pia Sörensen], determined that the key seems to be making a brownie mixture with very finely dissolved sugar, in sucrose form, with a carefully controlled amount of water in the mixture. This produces a thick mixture which can hold together against the gases bubbling out during the cooking process, and produces a nice glossy skin. Too much water, and the mixture isn’t viscous enough to hold up, leading to brownies full of pock marks, while alternative sugars like fructose and glucose likely disrupt the ordered structure of sucrose molecules necessary for a shiny surface.
Together, [Adam] and [Pia] do a great job of exploring the molecular chemistry behind the process, as well as ruling out several myths that have been perpetuated in the viciously insular brownie subculture. All they’re missing is a set of standardised reflectivity tests executed with an Arduino and some photodiodes, but we’ll assume that was just cut for time. We’ve seen other hacks in the realm of molecular gastronomy before, like this homebrew kitchen centrifuge. Video after the break.